My heart goes out to you and I understand that you would be upset with yourself but you can't let things like that eat at you. You were 12 at that point you didn't know any better. You cant let the bad memory take priority over the good ones. I'm sure your grandfather wouldn't want you beating yourself up for something that happened 11 years ago and I'm sure that's not how he remembered you and that's not how he would want you to remember him.

Thanks for the kind words. I know I can't let it eat at me, its just really hard sometimes. I definitely have many good memories of him. It's just one of those things that you're like "I wish I would've known" But thanks man.